The present invention is directed to color measurement and, more particularly, to a method for establishing accuracy consistency in the measurement of color measuring instruments located at a number of facilities.
Color measuring instruments are widely employed to determine whether the color of various articles being produced meets the specifications for the desired color of that product. Sometimes different manufacturers, and/or different locations of the same manufacturer, may be producing parts which are intended to have the same color so that they will match when assembled. Moreover, replacement parts should also have the same color as the originally produced parts.
If all production were to be measured by the same color measuring instrument, and assuming that the color measuring instrument were properly maintained and serviced, there would be no significant problem in ensuring that the measurement results are consistent for that instrument since it can be periodically checked using a set of color standards.
However, when production is taking place at a multiplicity of locations employing different instruments and even instruments of different manufacturers, consistency in measurements from instrument to instrument is unlikely, and, in fact, it is likely that there will be substantial deviation in the results which would be obtained from measurement of the same part on the different instruments. Unfortunately, there is even variation between sets of color standards used to measure the performance of calibrate the instruments. Some color measuring instruments tend to exhibit drift in the measurements which they will generate over a period of time. Obviously, if a manufacturer cannot be assured that all of the parts it is making which are intended to have the same color values can be tested to determine that they do so, there would be a need to match parts of the same color coming from different sources.
Accordingly, it is an object of the present invention to provide a novel method for establishing management control over a series of color measuring instruments at remote locations to ensure that the measurements obtained by use of different instruments are accurate and related.
It is also an object to provide such a method in which the individual facilities making parts can certify to the customer that the parts produced meet the color specifications established for the part.
Another object is to provide such a method in which a master color lab can maintain supervisory control over the measurement techniques and instruments being employed at a multiplicity of locations and provide corrective action.